1. Field of the Invention
The present invention relates to the investigation of semiconductor wafers. It relates particularly, but not exclusively, to the determination of the mass, weight and/or dielectric constant of a layer deposited on such a wafer.
It also relates to the investigation of thickness of layers deposited on such a wafer.
2. Summary of the Prior Art
It is already known to investigate the thickness of a layer on a semiconductor waver, but existing thickness methods are specific to the type of material applied to the wafer. For example, when the layer is an insulator deposited the layer, its thickness investigated by ellipsometry or spectral reflectivity, whereas if the layer deposited is a metal, its thickness is investigated by measuring its surface resistivity. When a layer is subsequently etched, its subsequent thickness may be measured by interferometry or by using a service profiler.